In a bowl, combine rolled oats, mashed banana, egg, and milk.
Add honey or maple syrup, vanilla extract, baking powder, cinnamon, and a pinch of salt. Mix until well combined.
Fold in any optional mix-ins.
Grease a small, air fryer-safe baking dish.
Transfer the oatmeal mixture to the dish.
Preheat the air fryer to 350°F (175°C).
Cook for 15-20 minutes, or until set and slightly golden.
Let it cool for a few minutes.
Serve warm with additional toppings if desired.